362 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Of the forty-seven rock-sections examined, Lithothamnion occurs in 

 thirty-five, and is decidedly the most abundant and most widely dis- 

 tributed organism. Many of the slides in which it is not found have 

 been dolomitized, and any organisms present have been removed. Prob- 

 ably Lithothamnion was present in some of these rocks originally. It 

 should be mentioned that the term Lithothamnion is used throughout 

 in the older and wider sense, and not as a generic name. 



Halimeda, the other calcareous alga present, is much less widely dis- 

 tributed. It occurs in nine sections, coming from Mango, Niue, and 

 Eua. It is much less stable than Lithothamnion, and this may account 

 to some extent for its more limited distribution. 



Echinoderm fragments (largely echinoid spines) occur in seventeen of 

 the specimens, and take an appreciable part in the composition of the 

 rocks. Polyzoa were found in twelve slides from eight of the fourteen 

 islands. They are most abundant in the Vavau rocks. 



Corals occur in fifteen sections, being represented in two cases by 

 alcyonarian spicules only. Since they undergo alteration rather easily, 

 they may have been present originally in some of the altered rocks, 

 but even taking this into account, they play a much less important 

 part in the formation of the limestones than might be expected. More- 

 over, a large proportion of the rocks were obtained from terraces 

 where the corals seem to be especially abundant, yet the actual bulk 

 of the terraces compared with the rest of the limestones is not 

 great. 



Of the Foraminifera, Carpenteria occurring in nineteen sections, and 

 Polytrema in twenty-one, are the most widely distributed and also the 

 most numerous individually. Carpenteria has probably had an even 

 wider distribution than appears, as it seems to undergo alteration fairly 

 easily. The genus Polytrema is commonly represented by P. miniaceum 

 Pallas, sp., but P. planum Carter also occurs. Both forms are found at 

 times intergrown with Lithothamnion, forming a mass consisting of layers 

 of the different organisms alternating. Polytrema, however, encrusts 

 various objects besides Lithothamnion. 



Gypsina was found in eleven sections, and is often very abundant. 

 Orbitolites occurs in ten sections, but is only abundant in the Niue rocks. 

 As a rule, not more than one specimen occurs in a slide. In sections it 

 possesses a burnt sienna color which is characteristic, although in some 

 cases where alteration has taken place it is block and opaque. Miliolina 

 occurs in eight sections, but does not make up a considerable part of any 

 of the rocks. It is commonest in Eua and Vavau sections. 



